From below them, a boom sounded, rattling the walls, shaking the ceiling. Tiles and brickwork cracked and flew, tiny pieces of shrapnel that cut and stung.

The man with the shaven head and broad bouncer’s shoulders stared out at the line of rocks that pointed towards the shore. His face was set, his body tensed.

Then he turned and spoke to them all: ‘Nothing has changed. Either we die here, or we take our chances out there. I know which I choose.’

With that, he stepped over into the sea. The water closed around his ankles, lapped up his shins. He bent over to steady himself, one hand against the wet, barnacled boulder, and took another step. His foot slipped slightly, and he had to use both hands to stay upright. When he glanced back, he was smiling, his teeth white against his soot-streaked skin.

The roaring from inside the station was too loud to ignore now. It sounded like an oncoming train, but overwhelming and inexorable. Everything was shaking, and this, surely, was the end. The stray, the Chinese-looking woman who’d joined them in the tunnels, didn’t hesitate. She jumped out and over, and didn’t look back.

‘Up, Mama, up!’ Mary dipped down and dragged at Mama’s arms. ‘Everybody up.’

Mama responded slowly, uncertainly, and Mary rounded on the man in the turban. ‘You. You’ve got to help.’

He did. He got behind Mama, pushed her towards the open door. Behind him, the red glow started to build.

‘Hurry. Out. Out.’ He reached out for the other two women and they climbed up him, almost pulling him over in the process.

Mama was still in the doorway, blocking it, feet against the jamb, hands braced against the uprights. Mary wasn’t gentle. She put her hand in Mama’s back and heaved her into the sea, letting the others jump past her and pick her up.

Then it was her and the turbaned man – boy, he was just a kid, like her – facing each other across the width of the open door.

‘This. This is fucking nuts, right?’

‘Where are we?’ His brown eyes were wide and wild, struggling to take any of the impossible view in.

‘We’re in London.’ She looked over her shoulder. The narrow door that led from the staircase to the corridor creaked, and jets of flame bored through the gaps. She watched Mama struggle and wail as a wave caught her full on, and heard the others shriek at the cold. She put one foot into the sea, felt the water rise up, fill her boot. The rest of her was burning. There was no choice, really. ‘And now we’re not.’

She pulled on the door, ready to swing it back shut, and the boy, already wet to his waist, jumped in again to help her wrestle it home. Neither of them gave any thought as to what the door might be attached to.